The use of surgical devices is quite common in many modern surgical procedures. Such devices assist surgeons in performing operations that were previously difficult or impossible to perform. However, many surgical devices, such as surgical lasers, electrosurgical units (ESU's), ultrasonic units, surgical drills, surgical power tools, endoscopic and laparoscopic tools, tools for use in open procedures, and any other tool to assist a surgeon in minimal evasive and evasive procedures, generate waste products during use.
In the case of surgical saws, drills and the like, the waste product generated consists of blood, bone chips, smoke and other particulate matter which may contain viruses, bacteria and other noxious and toxic substances capable of transmitting disease. In the case of ESU's and surgical lasers, the primary waste product is in the form of a smoke plume.
Health concerns raise a significant reason to remove smoke plumes. It is known that smoke plumes can carry active particles such as viruses, bacteria mycobacteria and other microbes or toxins. Additionally, chemical mixes used in medical procedures can generate hazardous vapors also found in smoke plumes. The particles and vapors found in a smoke plume may be transmitted to the staff performing the medical procedure, or the patient undergoing surgery, through contact with the plume. Furthermore, these particles and vapors can remain suspended in the operating room, thus exposing the next patient or surgical staff.
Government agencies have recently begun to investigate smoke plumes and now advise the removal or filtering of smoke plumes generated by laser surgery. See "OSHA Technical Manual--Section V--Chapter 1 Appendix V:1-3, Physical Agents", "OSHA Technical Manual--Section V--Chapter 1, Hospital Investigations: Health Hazards" and "Health Hazard Information Bulletin: Hazards of Laser Surgery Smoke", Apr. 11, 1988. This concern has extended to other procedures generating smoke plumes such as electrosurgery. See "Standard Interpretations and Compliance Letters--Hazards of Smoke Generated from Surgical Procedures" at http://www.osha-slc.gov. Furthermore, the "1996 Standard & Recommended Practices" issued by the Association of Operation Room Nurses, Inc. recommends removal of smoke plumes during electrosurgical procedures, and the Center for Disease Control and Prevention (CDC) and the National Institute for Occupational Safety and Health (NIOSH) issued in September of 1996 issued a Hazard Control II (HCII) entitled "Control of Smoke from Laser/Electric Surgical Procedures" similarly recommending removal of smoke plumes generated by electrosurgery.
Accordingly, it is desirable to have a system in place near the site of the surgery to remove such waste products before they come in contact with surgeons, nurses and other medical staff in near proximity to the surgery. This area is often called the "breathing zone". The most common system for waste removal is the surgical evacuator. The evacuator removes waste product by generating a partial vacuum in the vicinity of the site of the surgical procedure. Air, gas, liquid or other fluid containing the waste product is drawn through the evacuator, filtered to acceptable levels and vented.
In the past, various methods have been used to control the operation of evacuators. Early forms of control were direct manual operation of the evacuator. In this method, the surgical procedure was monitored continually by a member of the surgical staff. The surgical evacuator would be manually activated by the staff member upon commencement of the surgical procedure, and then manually deactivated at the termination of the surgical procedure. This system presented several problems. Typically it required the services of a staff member other than the surgeon, as the surgeon was preoccupied with performing the surgery at hand. In certain circumstances, members of the surgical staff would not remember to activate or deactivate the evacuator at the appropriate times. Thus, situations sometimes arose where smoke plumes generated by the surgical procedure were not removed through evacuation. Other situations would arise where the evacuator, although activated at the commencement of the surgery, was not deactivated at the termination of the surgery. This resulted in additional and unnecessary operation of the evacuator, thus reducing the effective life of filters implemented in the evacuator, along with increased wear and tear on particular components in the evacuator.
As a result, attempts have been made to solve such problems. In U.S. Pat. No. 5,108,389, a smoke evacuator system is disclosed in which a foot switch is provided. The switch is coupled to a smoke evacuator, such that operation of the foot switch by a surgeon causes the smoke evacuator to activate or deactivate. This invention, however, still requires conscious monitoring by the surgical staff. The surgeon or staff member must remember to operate the foot switch at the appropriate time to either turn the evacuator on or off. In addition, inadvertent movement by a member of the staff could cause the switch to accidentally activate or deactivate the evacuator at inopportune times during the surgical procedure. Hence, it is desirable to provide an automatic method of controlling the evacuator such that the evacuator is turned on contemporaneously with commencement of use of a surgical device, and turned off at approximately the same time that the surgical device is turned off.
One apparatus for providing automatic control of an evacuator is disclosed in U.S. Pat. No. 5,318,516. The '516 patent discloses an apparatus using a radio frequency (RF) sensor for automatic control of a smoke evacuator. The sensor detects stray RF energy emitted by the operation of the power supply of an ESU or surgical laser and activates an evacuator in response. Although this reference teaches use of an RF sensor to detect the operation of a surgical laser or ESU, it is desirable to develop a control apparatus which operates on other principles.
The presence of RF energy is very undesirable in an operating room. RF energy interferes with the operation of many other medical instruments which rely on electronic signals. The operation of devices such as pacemakers, monitoring units, and other sensitive pieces of electronic medical equipment may be disrupted by the presence of stray RF energy in the operating room. Hence, a movement is underway to develop operating rooms which minimize the presence of RF energy. Requirements for RF shielding on medical devices, and limitations on RF energy are now being implemented in various countries. Accordingly, it is very desirable to develop an apparatus that automatically controls the operation of an evacuator in the absence of RF energy.
U.S. Pat. No. 5,620,441 also discloses a remote switch apparatus for the automatic control of a smoke evacuator. This invention relies on the electrical characteristics of a conductor connected to a surgical device to automatically control an evacuator. The system of the '441 patent requires that a specialized inductive sensor be placed in immediate proximity to the conductor which connects the power supply and the hand piece of an electrosurgical unit (ESU). When power is provided to the handpiece, a high frequency electrical current passes from the power unit of the ESU through the conductor and induces a current flow in the inductive sensor, which in turn actuates the evacuator.
Because the inductive sensor of the '441 patent relies on a transformer to induce high frequency currents within a secondary winding, it may generate undesirable EMF within the operating room. For the reasons stated above, it is desirable to develop a switching apparatus which does not rely on either RF or high frequency electrical signals for activation and deactivation of an evacuator.